1. Field of the Invention
The present invention generally relates to a process and to an apparatus for the treatment of backwash effluent resulting from a backwashing operation carried out on an industrial filter. More specifically, the invention relates to a process and to an apparatus which utilizes a backwash filter to cleanse the backwash effluent from solids and other impurities released from the industrial filter during the backwashing operation, and wherein the resultant treated and purified backwash liquid is recycled for use in subsequent and repeated backwashing operations.
2. Discussion of the Prior Art
In many beverage and bottling plants currently in operation, industrial filters of the sand and carbon types are employed in the industrial processes which are effected therein. These sand and carbon filters are periodically or cyclically cleaned by means of a backwashing operation at which time a water-based solution or liquid is conducted through the respective filter in a countercurrent flow direction with regard to the flow through the filter during a normal filtering operation. The backwashing procedure is adapted to remove any solids and particulate material from the industrial filter in order to maintain the latter in an efficient operating condition. Typically, a backwashing operation necessitates the employment of a large volume of water and, during this operation, varied amounts of heavy solids are dislodged and, as a consequence, released from the industrial filter for removal therefrom.
In a typical backwashing operation of this nature, the effluent from the backwashing operation is dumped into the general effluent discharge of the plant, thereby producing a number of detrimental effects. Thus, for example, the backwash liquid frequently is rather expensive, since it may be constituted of a water-based solution which is treated with costly chemical additives in order to maintain its pH and chlorination values within predetermined parameters for imparting maximum sanitizing properties thereto during backwashing operations. Accordingly, dumping the backwash effluent into the general effluent discharge of the plant and its concomitant single use results in the discharging of a rather costly treated backwash liquid, frequently rendering the operation uneconomically expensive. Furthermore, the discharge of the backwash effluent into the waste treatment system of the plant often causes the imposition of a very large and, occasionally, sudden demand on that system. The waste treatment system is heavily or shock loaded as a result of the large quantity of backwash liquid involved in the operation and, in addition, because the solution is chlorinated, and carries along appreciable quantities of solids and particulate material which is backwashed from the industrial filter.
Heretofore, various kinds of systems have become known in the prior art whose function is the reclamation and reuse of the backwash water, however, these prior art systems do not attempt to either control or remove the heavy solids released from the industrial filter during the backwashing operation. In addition, the prior art systems are not concerned with the optimization of the backwashing operation by maintaining the chlorination and acidity or pH values of the backwash liquid at levels which would result in the most efficient performance in the backwashing function. The present invention, thusly, would have excellent use in conjunction with DeLonge U.S. Pat. application No. 832,283, assigned to a common assignee, and which is directed to a process and apparatus for the treatment of aqueous waste materials and effluent from bottling plants and installations. The DeLonge process and system is particularly concerned with the removal of biological oxygen demand (BOD) from the waste materials, and is also directed toward the treatment of the many different types of effluent discharges of a beverage or bottling plant, but is not specifically directed towards the problems associated with the reclamation or recycling of backwash effluent resulting from the backwashing operation of an industrial filter. Utilizing the invention process and apparatus in the treatment and recycling of the backwash liquid in combination with the process and system in the copending DeLonge patent application would provide an efficient and economically viable installation for the treatment of industrial effluents not in any manner taught nor contemplated in the prior art.
Chapman et al U.S. Pat. No. 3,592,743 discloses a system for the treatment of industrial and domestic waste water having a relatively high solids content, wherein the waste water is recycled in order to reduce the usage of water. More particularly, the Chapman et al system is designed for use in areas in which the available water supply is rather restricted and, moreover, wherein waste disposal systems are already present and in use. The processes and systems disclosed by Chapman et al are basically quite different in overall purpose and structure from those of the present invention in that the former is not directed to the recycling of treated backwash water analogous to that contemplated herein.
Kirk U.S. Pat. No. 3,892,659 discloses a waste water purification system in which waste water and activated sludge are admixed in a receiving well, from which the admixture is then later withdrawn. Thereafter, oxygen is introduced into the admixture and the latter is conducted through a series of contained reaction stages. The admixture or solution is then divided into two unequal flows, of which the main flow is recycled directly to the receiving well, and with the second flow of lesser volume being directed to a clarifier from which activated sludge is recycled to the receiving well. The arrangement and process disclosed in Kirk is employed in the recycling of purified water, but the specific arrangement and process is quite distinct from that of the present invention and is not designed for the treatment and reclamation of backwashing liquid.
Besik U.S. Pat. No. 4,008,159 discloses a waste water treatment system for the recycling of waste water which incorporates a four-stage operation for effecting the successive removal of various contaminants present in the water. This patent is also quite different in its overall objectives and arrangement from the inventive process and system disclosed in the present patent application in that it does not relate to the treatment and recycling of backwashing liquid.